Blind shell piston accumulator



NOV- 24 1964 E. M. GREER BLIND SHELL PIsToN AccUMuLAToR Filed Deo. 28. 1960 v INVEN TOR.

PA/mvp f6/227? BY JM? United States Patent G 3,158,180 BLIND SHELL PISTON ACCUMULATOR Edward M. Greer, Beverly Hills, Calif., assignor to Greer Hydraulics, Inc., a corporation of New York Filed Dec. 28, 1960, Ser. No. 78,936 4 Claims. (Cl. 13S- 31) This invention relates to the -art of pressure vessels, lmore particularly to a pressure accumulator of the piston type.

As conducive to an understanding of the invention, it is noted ythat where in pressure vessels, such as pressure accumulators of the piston type closure members are used at each end of the vessel of diameter substantially equal to the internal diameter of the pressure vessel itself, the relatively large area between the closure member and the pressure vessel defines a region that is likely to permit leakage more particularly on the g-as side of the accumulator as gas is much harder to seal than oil.

It is accordingly among the objects of the invention to provide a piston ltype pressure vessel, more particularly a piston accumulator, which has a minimum number of parts and may be readily fabricated at lrelatively low cost. and which will greatly minimize likelihood of leakage oi gas from the gas side of the device.

According to the invention, these objects are accomplished by the arrangement and combination of elements hereinafter described and more particularly recited in the claims.

In the accompanying drawing is shown one of various possible embodiments of the several features of the invention, the single iigure is a longitud-inal sectional view of the pressure accumulator.

Referring now to the drawing, the pressure accumulator comprises a substantially cylindrical casing 11 of rigid material capable of withstanding high pressure.

The casing is formed by drawing a shell of suitable metal so that the major port-ion of the body of the casing is cylindrical, having a threaded opening 12 at one end, with the other end 13 of the casing being hemispherical as shown. The hemisphe-rical end has an axial port 14 therein of relatively small diameter, i.e. a fraction of the diameter of the casing itself, said port defining the gas inlet port of the accumulator.

The end 12 of the casing is closed by means of a plug 15 having an axial bore 15' defining the liquid port of the accumulator. As sho-wn, the plug 15 is cylindrical at its inner end, as at 16, being of diameter just slightly less than that of the casing 11 so that it may fit therein with but a slight clearance. The cylindrical portion 16Y of the plug has an annular groove 17 in which an O ring 18 is positioned to provide a seal.

The plug 15 is of reduced diameter outwardly from said cylinder portion 16, defining an annular shoulder 19 and said reduced diameter portion is substantially conical, tapering inwardly toward the axis of said plug, as at 21. The outer extremity of said plug is also cylindrical, as at 22, and desirably is threaded to receive a lock nut 23 of outer diameter such thatits periphery will rest against the thread opening 12 of the casing 11, as is clearly shown.

To retain the plug 15 in the casing 11 under the pressure contained therein, a lock sleeve 24 is provide-d externally threaded to coact with corresponding threads on the inner surface of the casing 11 adjacent the end 12 thereof. The outer end of said lock sleeve 24 desirably has an out- Wardly extending flange 25 adapted to seat on an annular shoulder 26 formed at the end of the casing 11. The inner end of the lock sleeve 24 desirably is bevelled on its outer surface as at 27 and the annular shoulder 19 of the plug 15 is adapted to abut against said bevelled inner end, as shown, to limit outward movement of the plug 15.

3,158,180 Patented Nov. 24, 1964 ICC The lock sleeve has suitable conformations 20 at the end remote from liange 25 to permit insertion therein of a suitable tool for rotation of the lock sleeve 24 when the unit is to be disassembled.

By reason of the ange 25, the lock sleeve 24 c-an only be inserted with the conformations 20 thereof at its lower end. Hence as the side wall of plug 15 is closely adjacent the locking conformation 20, it is apparent that such plug cannot be removed so long as there any substantial pressure remaining in the accumulator.

Thus, when there is pressure in the accumulator, the plug 15 will be urged outwardly so that its shoulder 19 will abut against the inner end of the lock sleeve 24, retaining the plug in position. So long as there is pressure in the unit, no access is provided to permit insertion of a tool into .the conformations 20 to rotate the lock sleeve. This sleeve can only be rotated when the pressure in the accumulator has been reduced to a point such that the plug 15 can be moved inwardly after the lock nut 23 is removed to provide access to the conformations 20 to permit insertion of a tool that can engage the appropriate conformations on the inner surface of the lock ring for rotation of the latter for remo-val of the same.

Slidably mounted in the casing 11 is a piston 31 which desirably comprises a sleeve 32 open at one end, as at 33, X

and having its other end 34 closed, said closed end being substantially hemispherical as shown, and formed as an integral part of the sleeve 32 as by draw-ing the entire assembly. Preferably formed integral with 4the sleeve 32 is a pair of spaced annular members 35, 36 of outer diameter but slightly less than the inner diameter of the casing 11 to provide but slight clearance therebetween suiicient for ready movement of the piston. Each of the annular members has an annular groove therein in wh-ich an 0 ring 37' is positioned to provide a seal and the annular member 36 adjacent the oil chamber 38 of the accumulator has a passageway 39 therethrough to provide co-mmunication between the annular space 41 between the annular members 35, 36 and the oil chamber 38 to prevent excessive pressure developing in said space 41 in use of ythe device which might cause extrusion of said O rings.

As shown, the inner surface of the plug 15 has a recess 42 therein of conliguration complementary to that of the hemispherical end 34 of the piston 31 so as to receive the latter when the piston is bottomed against such plug 15. The open end 33 of the piston desirably has its outer perip-hery bevelled, as at 43, so that when such bevelled end abu'ts against the hemispheri'cal end 13 of the casing 11 it will not wedge in place, thereby permitting free movement of the piston.

To reinforce the open end 33 of the piston 31 a ring member 30 is provided, externally threaded to coact with corresponding threads on the inner surface of the open end of the piston.

By reason of the use of the drawn-type shell with the henri-spherical end 13 that is an integral part of the unit, it is apparent that there will be no opening on the gas side of the accumulator that requires a plug for closure of diameter greater than a fraction of the diameter of the casing 11. Thus, the only opening on such gas side is the port 14 through which gas is directed and this port is of course of relatively small diameter.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter conta-ined in the above description, or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A pressure vessel comprising a cylindrical forged casing having a cylindrical opening at one end and having its other end closed `and substantially hemispherical, said closed end being an integral part of the casing, a piston having a hemispherical portion at one end, said piston being slidably mounted in said casing, the end of the piston in the chamber of said pressure vessel adjacent the hemispherical end of the easing having its outer periphery bevelled and adapted to abut against the inner surface of the hemispherical end oi' said casing, a plug releasably secured in the open end of the casing, said plug having a recess in its inner end of curvature complementary to the curvature of the hemispherical end of said piston to yreceive the latter, said plug having a port therethrough for fluid, said closed end having a port therethrough of diameter a fraction of the diameter of said casing.

2. The combination set forth in claim l Iin which said piston comprises a sleeve, one end of which is open and the `other end of which is closed, said closed end of the sleeve being substantially hemispherical and integral with the sleeve, and a reinforcing ring is positioned in said sleeve at the open end thereof.

3. The combination set forth in claim 1 in which said end plug has ya cylindrical portion at its inner end and is of reduced diameter outwardly from said cylindrical porplug, the outer end of said lock sleeve having an outwardly extending ange and the end of said casing having an annular seat adapted to receive said flange to limit the inward movement of said lock sleeve, said lock sleeve having tool insertion means at the inner end thereof to permit rotation of said lock sleeve for removal thereof, said tool insertion means being aligned with the inner end of the reduced diameter portion of -said plug when the shoulder of said plug abuts against the inner end of said lock sleeve.

4. The combination set forth in claim 3 in which a lock nut encompasses the cylindrical outer end portion of said plug, and abuts against the end of said casing.

References Cited in the tile of this patent UNITED STATES PATENTS 2,734,531 Bizak Feb. 14, 1956 2,828,760 Taylor et al. Apr. 1, 1958 2,845,138 Gageby V July 29, 1958 

1. A PRESSURE VESSEL COMPRISING A CYLINDRICAL FORGED CASING HAVING A CYLINDRICAL OPENING AT ONE END AND HAVING ITS OTHER END CLOSED AND SUBSTANTIALLY HEMISPHERICAL, SAID CLOSED END BEING AN INTEGRAL PART OF THE CASING, A PISTON HAVING A HEMISPHERICAL PORTION AT ONE END, SAID PISTON BEING SLIDABLY MOUNTED IN SAID CASING, THE END OF THE PISTON IN THE CHAMBER OF SAID PRESSURE VESSEL ADJACENT THE HEMISPHERICAL END OF THE CASING HAVING ITS OUTER PERIPHERY BEVELLED AND ADAPTED TO ABUT AGAINST THE INNER SURFACE OF THE HEMISPHERICAL END OF SAID CASING, A PLUG RELEASABLY SECURED IN THE OPEN END OF THE CASING, SAID PLUG HAVING A RECESS IN ITS INNER END OF CURVATURE COMPLEMENTARY TO THE CURVATURE OF THE HEMISPHERICAL END OF SAID PISTON TO RECEIVE THE LATTER, SAID PLUG HAVING A PORT THERETHROUGH FOR FLUID, SAID CLOSED END HAVING A PORT THERETHROUGH OF DIAMETER A FRACTION OF THE DIAMETER OF SAID CASING. 